Gas turbine engines such as those used as aircraft turbojets or turbofans typically comprise a rotating fan, compressor and turbine that are axially mounted to one or more coaxial shafts for rotation about a central axis of the engine. The shafts are rotatably supported by at least two bearing assemblies and the front-most bearing assembly in the direction of fluid flow in the engine also prevents axial movement of the shaft within the engine case and is referred to as a “thrust bearing assembly”. Despite thrust bearing assemblies typically being machined to tight tolerances, a small amount of axial play in the thrust bearing assembly exists. This play is undesirable as it causes noise and vibration of the engine when the engine is in operation. Much of this play can be eliminated by exerting a forward load on the bearing, for example by pressurized air from the compressor. A forward force caused by the pressurized air from the compressor is exerted on the rear portion of the compressor section and is transferred through the shafts to the thrust bearing assembly. However, due to size constraints on the engine and performance requirements of the compressor section, the amount of pressure exerted in conventional engine designs, may not provide adequate forward load on the thrust bearing assembly.
Accordingly, an apparatus for adjusting a thrust load on a rotor assembly for a gas turbine engine is desirable in order to improve thrust bearing load control.